Machine for milling threads



Jan. 28; L930. e. E. MIRFIELD 1,745,035

MACHINE FOR MILLING THREADS Filed Nov. 1. 1927 llSheets-Sheet 1 w rzvss's I A BY w Q Q 7 fiTTOHIYEKS Jan. 28, 1930. G. E. MIRFIELD 1,745,035

MACHINE FOR MILLING THREADS Filed Nov. 1, 192'? ll Sheets-Sheet 2 A/VENTOFT Jan. 28, 1930. MIRFIELD 1,745,035

MACHINE FOR MILLING THREADS Filed Nov. 1, 19 27 11 Sheets-Sheet 3 W. Gea eEMn/bZdA Jan. 28, 1930. G. E. MIRFIELD 7 1,745,035

MACHINE FOR MILLING THREADS Filed Nov. 1, 1927 11 Sheets-Sheet 4 zzaf / NVE/V TOR w I'TNESS g B) Jan. 28,1930. G. E. MIRFIELDY 1,745,035

MACHINE FOR MILLING THREADS Filed Nov. 1, 1927 11 Sheets -Sheet 5 I/IIIA Jan. 28, 1930.

Filed Nov. 1

G. E. MlRFlELD MACHINE FOR MILLING THREADS ll Sheets-Sheet 6 A L i W- lNVE/VTOI? J11 J13 GizwzgeEMgOe/kl WITNESS Jan. 28, 1930. e. E. MIRFIELD MACHINE FOR MILLING THREADS 192 11 Sheets-Sheet 7 Filed Nov. 1

' WITNESS Jan. 28, 1930. MlRFlELD 1,745,035

MACHINE FOR MILLING THREADS Filed Nov. 1, 1927 11 Sheets-Sheet 8 ELF, f5.

INVENTO? G za/96 w 7 Y flTTORNEKS Jan.28, 1930. GEMIRFIELD 1,745,035

MACHINE FOR MILLING THREADS Filed Nb). 1. 1927 11 Sheets-Sheet 9 INVENTGI? Ge. 013.6 JkM ym flTToENEYS Jan. 28, 1930. G. E. MIRFIELD MACHINE FOR MILLING THREADS Filed Nov. 1. 1927 11 Sheets-Sheet l0 n" u m k Eim p /Zn". RN WM u WITNESS Jan. 28, 1930. G. E. MIRFIELD MACHINE FOR MILLING THREADS l1 Sheets-Sheet ll Filed Nov. 1, 192'? m NNW WITNESS Patented Jan. 28, 1930 UNITED STATES GEORGE E nrnnmLn,

OF YOUNGSTOWN, OHIO MACHINE FOR MILLING THREADS Application filed November tubes and I will more especially refer herein to their employment for that purpose,- itbeing, however, understood that such machines are capable of being utilized for other purposes as well, such as forming threads or performing other milling operations on the ends of rodsbr other articles of like character.

In United States Letters Patent No. 1,611,- 122 granted to me December 14, 1926, I disclosed and claimed a novel method for mill-' ing threads on pipes, tubes and the like, as Well as one form of'machine adapted for the performance of the said method, while in an application for United States Letters Patent filed by me November 29, 1926, I disclosed and claimed another form of machine operable in accordance with the said method; the

. present'invention'relates to still another form of machine als operable inaccordance with said method in its broader aspects and in some respects constituting an improvement over the priorma'chines to which reference has just been made, and, consequently, contemplates the provision of a machine adapted forjthe production of smooth and accurate threads, either straight or tapered, with a minimumexpenditure of time and labor and Within the tolerances and of the standards required in modern machine shop practice. Further objects, novel features, characteristics and improvements comprehended by the invention will hereinafter more fully appear.

As in the earlier machines to'which I have referred, I employ in a machine constructed in accordance with the present invention, a plurality, conveniently a pair, of rotatable milling cutters respectively of suitable character to impart to the work a roughing cut of sufficient depthto remove the scale andtrue the surface which is to be threaded. and to form the desired threads thereon, and so arrange these cutters in their relation to each other-and to the work that the roughing cut ter will operate on the rotating work at a point in advance of that at which the thread ing cutter operates thereon with the result ,1, mar. Serial No. 230,226.,

that the threading cutter is relieved from the duties of penetrating the scale and truing the work'and relegated to the sole duty of cutting -into the clean metal exppsed by the roughing cut for a depth suflicient to form the required threads, thereby contributing to their accuracy and materially enhancing the life of the cutter. p

Moreover, for the production of tapered threads, I employ cutters tapered longitudinally with respect to their axes of rotation in conformity with the taper of the thread which it is desired to produce and of substantially the length of such thread, and provide the threading cutter with a plurality of annular teeth having the profile of the? form of the desired thread but no pitch so that by efiect- -ing substantially'a single revolution of the work with respect to this cutter and, simultaneously moving the work longitudinally for a distance substantially equal to the pitch of the thread to be out while effecting slight relative movementbetween thevwork and the cutter in a direction substantially normal to the axisof the latter, a complete and accurate tapered spiral thread of the desired length will be formed in'the work.

For efiecting these results I therefore provide a machine which in its preferred embodiment comprises, among other things, separate roughing and threading cutters and means for supporting, adjusting and driving both cutters in a manner to avoid disalignment or looseness thereof with consequent chattering and resulting imperfection in the work; means for feeding the roughing cutter to depth in the work; means for feeding the threading cutter to depth in the work after the roughing cutter has traversed a limited portion thereof and rendered it sultable forthe reception of the-threading cutter;

means for chucking and centering the work, for imparting rotation thereto and for eflect- ,ing the requisite relative longitudinal movement between the-work and the threading cutter necessary for the production of a continuous spiral thread when employing a cutter having formteeth without pitch; means for effecting gradual relative movement between the threading cutter and the work in a direction substantially normal. to the longitudinal axis of the latter to thereby enable t production of accurate tapered threads by adequately compensating for the difference in radial magnitude of iiferent portions of the complete thread' means for effecting the return of certain of the parts to initial or starting position following the completion of the threading of one piece of work to thereby place the machine in condition for the reception of the following piece and means for substantially automatically effecting the requisite movements of the cutters and other various elements and parts in suitably timed and correlated relation with each other from the initiation to the completion of the threading cycle as performed on each consecutive piece of work from the time of its introduction into the machine to the time of its removal therefrom.

To enable those skilled in the art to comrehend and practice the invention, I have ilustrated in the accompanying drawings and will now proceed to describe one form of the machine constructed in conformity with the principles thereof, it being however to be distinctly understood that means and instrumentalities other than those to which reference wilIbe made may be utilized if desired without departing from the spirit and scope of the invention; I therefore ,do not in any way confine or limit myself in the practice of the invention to the employment of the specific features of design, construction and arran ement of the particular machine herein disc osed.

Referring now to the drawings, Figs. 1 and 1 together constitute a top plan view of the machine, the ortion shown in Fig. 1' being omitted from ig. 1 for lack of space; Fig. 2 is a front elevation of the machine and Fig. 3 is an elevation of the ri ht hand end of the machine as viewed from t e front. Fig. 4' is an enlarged view of the work container and adjacent parts, principall 'in central vertical longitudinal section, an Fig. 5 is a fragmentary vertical section on line 55 in Fig. 6. Fig. 6 is .a horizontal staggered section on line 6-6 in Fig. 4; Fi s. 7 and 8 are fragmentary top plan views 0 certain of the parts shown in Fig. 6 but in difierent positions,and Figs. 9 and 10 are respectively transverse vertical sections on lines 99 and 10-10 in Fig. 4, these two figures, however, being on a slightly smaller scale than Fig. 4. Fig. 11 is a fragmentary view, partially in plan and partially in horizontal section, of the container drive clutch shifting mechanism and adjacent parts and Fig 12 1s a front view in elevation of a portion of said mechanism with the cap which normally covers the same removed. Figs. 13, 14 and 15 are respectively fragmentary detail views of certain portions of the clutch shifting mechanism viewed as a when looking to the left in Fig. 12, the clutch being shown in these views in different positain parts of the timing mechanism, the cap normally covering the same and which is shown in position in Fig. 3, bein removed, and Fig. 21 is a vertical section on line 21-21 of Fig. 20. Fig. 22 is a fragmentary detail section on line 22-22 of Fi 20 and Fi 23 a fragmentary plan view 0 portions 0 the mechanism through which the requisite movement of the threading cutter in a direction substantially normal to the axis of the work is effected in the production of a tapered thread. Figs. 24, 24, 24 and 24 are respectively diagrammatic views showin the relative positions of the cutters and t e pipe at different times during the threading cycle. The arrows on the section lines in all cases indicate" the direction in which the sections are taken and the same symbols are employed to designate the same parts in the various figures. Moreover, no attempt has been made in the drawings to illustrate the wiring or switches comprising the circuits in which the several motors are included nor the oil cups or other'means provided for effecting adequate lubrication of the various moving parts.

As comprehension of the construction and operation of the'machine will be facilitated by reference at this point to its general arrangement I shall therefore first briefly refer to its General assembly The base 1 of the machine is provided adjacent one end with a vertically extending pedestal 2 which may for convenience'be cast hollow and integral with the base. At the upper end of this pedestal are disposed a air of heads which are respectively slidab e horizontall toward and away from the center line C/ of the machine indicated on Fig. 1. One of these heads is operative to support the roughing cutter spindle and the driving mechanism therefor including a driving motor which is mounted on the head while the other head is operative to similarly' support the threading cutter spindle together with its driving mechanism and driving motor. Preferably fluid actuated means are also provided for reciprocating each of the heads upon the pedestal, the operation of said means being controlled through suitable timing mechanism so as to bring about the desired movements of the heads at proper times in the threading cycle.

Thecutter spindles are so arranged that the cutters respectively carried thereby will lie substantially midway-between the ends of the base and of course at a considerable elevation thereabove while disposed adjacent the opposite end of the base from that at which the pedestal is positioned are the means for holding the work and imparting to it the requisite movements of rotation and translation, generally corresponding to the mechanism which in my aforesaid application, Serial No. 151,281, I have termed the fixture. Said means comprise, generally speaking, a hollow container through which the work extends so that the end which is to be threaded will project between the cutters, a chuck carried by the container and operative to grip the work and.constrain"it to rotate with the container and a housing in 23 which the container is journaled, in association with driving mechanism operative to rotate the container and simultaneously cause longitudinal movement thereof while the thread is being cut and to then effect a quick b return of the container to initial or starting position by moving it, longitudinally in the opposite directon'while it is prevented from rotation, these several movements together with the requisite movements of the cutters 3o timing mechanism, to which reference has already been made, and which is so interconnected with the container drive and 'return mechanism as well as the cutter'feeding mechanism that the various movements of the container and cutters are brought about in properly timed relation with each other.

With this general'description in mind reference may now be made more specifically to the various elements of the machine.

Gutter heads aha? adjacent mechanism nally spaced transversely extending horizontal ways 3 upon which the'heads 4' and 5 are slidably held in position by-overhanging flangesformed on the heads and keepers'6 secured thereto and extending beneath the Ways (Fig. 21). The head 4 which supports 59 the roughing cutter R has a pair of integral longitudinally spaced inwardly overhangin arms 4 in' which the roughing cutter sp ndle 7 is journaled in suitable bearings preferably of the taper collet type or other type capable of adjustment to compensate forradial as well as longitudinal wear or end playas it is most important for the production-of a satisfactory thread that the spindles be constrained to run absolutely true. The 69 cutter spindle which I prefer to employ are very clearly illustrated in Fig. 18 and re-,

quire no extended description as they will be clearly understood by those familiar with the 'art; it will be noted, however, that inbeing effected through the medium of'the' construction and mounting of the roughing stead of molmting the roughing cutter R directly on anintegral extension of the spindle I prefer to mount the cutter as shown in said figure on a cylindrical boss-or extension 9 integral with a face plate 10 havin on its opposite side an integralplug 10' which seats in a bore 11 in-the end of the spindle, the face plate being removably secured on the latter by bolts 12 so that it may vbe readily taken off. This arrangement is of advantage in that it permits the face plate and parts integral therewith and which form the actual mountingfor the cutter to be hardened and accurately suring'the proper alignment of the cutter ground, thereby in 7 with the spindle, while in case of damage to the mounting the latter may be readil replaced without replacing the entire spindle-- as would be necessary if the cutter were mounted directly thereon.

The drive of. the roughing cutter spindle i is effected from a motor RM which is mounted on the head 4 and through a flexible coupling 15 drives a worm shaft 16 journaled in a housing 17 mounted over the spindle 7 which in turn carries a worm gear 18 cooper ative with a worm 19 on the shaft. It is thus apparent that the drive of the spindle is effected very directly from the motor, the necessary speed reduction being brought about solely through the worm and worm gear; consequently the rotation of the spindle is, extremely smooth and without backlash or lost motion. Y

- Thearrangement and drive of the threading cutter spindle 20 are substantially the same as that of the roughing utter spindle just described, the threading cutter spindle being mounted in arms 5, extending from the head 5 and driven in like manner from a motor- TM carried'by that head through the medium of a coupling 21, and worm shaft 22, jour- The pedestal 2 is provided with longitudinaled in a housing 23 and carryin a worm 24 cooperative with a worm gear 25 eyed to the spindle 20. V I

It will thus be apparent that the mounting of both spindles is extremely rigid, the bearings of the spindles being relatively widely separated longitudinally and the arms in which they are disposed being very heavy and atively great diameter compared with the diameter of the cutters R and T, the point of application of power to the gears is at a much greater distance from the axes of the spindles than are the points at which the cutters engage the work, in consequence of which any slight" errors or imperfections inthe gears and worms are not duplicated directly in the work but if they appear therein at all, appear provided with a pair 0 111 a reduced amount. I therefore consider my method and means of mounting and driving the cutter spindles as an extremely important im rovement in the art, for as a result thereo a, much more perfect and finer a pearing thread and one which is devoid of c atter marks and other imperfections can be produced; on the other hand said mounting and driving means are of an extremely simple character, comprise but few parts, are not liable to get out of order and require adjustment only at long intervals.

Gutter feeding means In accordance with the resent invention, the axes of the cutter spin les and in turn of the cutters are disposed in the same horizontal plane as the axis of the work and the cutters are arranged to operate on the latter at opposite ends of its horizontal diameter. Towards the end of each threading cycle, as hereinafter described, the cutters are moved outwardly away from the threaded work to permit its withdrawal from the machine and the insertion of the following piece respectively and it is therefore requisite after the piece has been chucked to first move the roughing cutter into engagement therewith, thereafter, at the expiration of a predetermined interval, to move the threading cutter into like engagement, to then, interval retract the roughing cutter to initial position after it has completed its duty and nally to similarly retract the threading cut- 0 ter, thus again p acing both cutters in such position thatthe threaded work may be withdrawn from the machine and the next piece of work inserted between the cutters. Additionally, to enable the machine to be used for threading pipe of different diameters, means must be provided to enable the cutters to be properly set for operation on the different sizes. and also for-different depths of cut on the same size of pipe, and reference will now be made thereto as well as to'the means for moving the heads in and outafter the cutters have been initially set.

17, the head 4 is As best shown in Fig.61 d 1 epen ing ugs and 31, through which extends an adjusting shaft 32 provided at its inner end with a keyway 33; this end of the shaft extends through the lug 30 and is prevented from turning therein by a set projects into the keyway. Adjacent to lug 31 the shaft is externall threaded and is surrounded by an interna 1y threaded sleeve 35 extendin through and rotatable in the lug 31 and all thrustbearings 36 and 37 are disposed on opposite sides of the lug between a shoulder 35 and a nut 35 on the sleeve. Adj acent the outer end of the sleeve whereby endwise movement of the latter is prevented a Wk rm ear 38- is keyed thereto whilfia worm sha t 39, carrying a worm sing e after a further screw 34 whose pointbracket 41 secured to an head, this shaft be- 42 p0siti0ned at its is journaled in a adjacent portion of the ing rotatable by a crank outer extremity. Thus, by rotation of the crank, sleeve 35 can be correspondingl rotated upon the threaded portion of a justing shaft 32 so as to move the latter longitudinally, said shaft being incapable from rotation on its own axis as above described. Consequentl the'inner end of the shaft 32 projecting t rough-the lug 30 may in this manner be moved toward or away from a fixed stop 43 bolted to the upper surface of the pedestal beneath the head in alignment with the shaft. 'As the reduction effected between the rotational speedof the shaft 39 and sleeve 35 is considerable and since for each revolution of the sleeve the longitudinal movement of adjusting shaft 32 is very small, the threads on the shaft bein preferably" of relatively-low pitch, a revolution of the crank effects a very fine adjustment of the adjusting shaft 32 so that in effect a micrometer adjustment thereof is provided. Preferabl a locking screw 44 is arranged to hold t e shaft 39 in adjusted position, while, as shown, the shaft may be threaded and rovided with an indicator 45 cooperative wit a suitably positioned scale 46 in such. manner that as the shaft is rotated the indicator will travel therealong and thus give a visible indication of the adjusted position of adjusting shaft 32.

It will be apparent from the foregoing that the ossible inward movement of'the head 4 is imited by engagement of the end of the adjusting shaft with stop 43 so that the further the head is moved inwardl on the adj ustin shaft, the further will the ead move inwar y toward the center line of the machine before its progress is arrested. For effecting the inward and outward movement of the head, fluid operated means are preferably employ ed, comprising a cyhnder 50 enclosing a piston connected with the outer end of adjusting shaft 32 and supplied with oil or other flui under pressure on opposite sides of the piston by means of pipes 51, ex-

)tending to an oil gear pump which, to ether with the necessary valve mechanism or effecting reversal of direction of flow throu h the pipes, is enclosed in a housing enera y designated as OGabolted to the en face of the pedestal or other convenient point of support. As oil gear pumps of this character are well known and in common use and as the same forms no part of the present invention, save" as one o the romponent elements of the o erative combination of the machine, exten ed description thereof would be superfluous. Power for operating the oil gear pumpzmay be su plied by a suitably positioned motor-0G through a driving chain 0, this motor bein also conveniently utilized for driving a lu ricating oil pump able piping OP, a circulation of oil or otherlubricant is directed over the cutters and,

other parts of the machine.

' Substantially similar mechanism is utilized for adjustably limiting the inward movement of the threading cutter head 5, comprising, in brief, an adjusting shaft 55, sleeve 56, worm 58, shaft 59 and crank 60, while a cylinder 61 having a piston connected with the shaft and in turn connected piping 62 with another oil gear pump OG driven from motor OGM by a chain C is arranged in like manner for moving the head in and out. The cylinders 50 and 61 are respectively mounted on suitable brackets 63 secured to opposite faces of the pedestal.

It should be noted, however, that the in.- ner end of the adjusting shaft 55 does not cooperate with a fixed sto'p corresponding to the stop 43 but is forked and provided with a cam roll 64 cooperative with a cam 65 which acts as a stop to limit the inward movement of the head in a manner generally similar to stop 43 with respect to the roughing cutter head. The function of cam 65 and adjacent mechanism will hereinafter more fully appear.

It will thus be evident, particularlyfrom an inspection of Fig. 17, that by suitable adjustment of the adjusting shafts 32 and 55 the extent to which the roughing and thread ing cutter heads can move inwardly may be varied as desired, and further, that when high pressure fluid is supplied to the pipes leading to the outer ends of the cylinders 50 and 61,

the heads will bemoved inwardly until their;

progress is arrested by engagement of their respective adjustingshafts with stop 43 and cam 65 and that so long asthe pressure is maintained on the outer sides of the pistons the adjusting shafts will be continuously urged against the stop and cam, but as soon as the fluid pressure is released from the outer side of the" pistons and exerted against the inner sides thereof, the heads will move outwardly in opposite directions from the center line of the machine for a distance determined by the possible outward movem nt of the pistons in the cylinders.

I have found in practice that the use of I fluid operated means of the general cha acter of those to which reference has been made is extremely satisfactory for effecting the requisite movement of the heads, but I do not confine myself exclusively to the use of such means as other means may be utilized for that purpose if desired.

Gontaz'ner mechanism extends when in operative position in the machine, as well as to the adjacent mechanism through which the container is supported and the means for gripping and holding the work relatively immovable with respect to the container.

The container is supported on a pad 71 which is integralwith the main base 1 adjacent the opposite end thereof from the pedestal and upon which rests the container hous- .ing base 72 adapted to be secured to the pad by bolts 73 having heads arranged to .slidably engage in undercut slots 74 in the pad. To enable adjustment of the container housing towards or away from the pedestal, an adjustin'g screw 7 5 is provided which coacts with a nut 7 6 disposed in a recess formed in a heavy block or bar 77 extending under the center 01 the'housing base 72 in a groove in the pad and connected to the housin base by a heavy vertically extending pin 38 The outerend of the screw projects through and is prevented from longitudinal movement in a bracket 79 secured to" the base 1, so that by rotating the screw, the bar, and in turn the base 72 through its connection to the bar by pin 78, can bemoved in or out when the bolts 7 3 are loosened.

' The container is rotatably journaled in a hollow housing 72 rising from the housing base and adapted to support a substantially semi-cylindrical hollow cap 80 removably secured in place by bolts 80. Toward the front of the machine the base of the housing is extended to form a box-like casing 72", adapted to contain certain of the'operating mechanisms and closed'on its front side by a removable cover plate conveniently formed with a lower section 81 and an upper section 81'.

At its forward-end, that is, its end adjacent the pedestal, the container is provided with a suitable chuck by means of which the pipe or other Work is' operatively locked to the container; This chuck may be of any suitable construction, though I prefer to use one having a plurality of radially movable jaws 82 supported in an annular plate 83 having a rearwardly extendingflange which is screwed into a bushing 84 seated in the end of the container and rigidly secured thereto. As the interior diameter of the container is desirably of the largest pipe which the machine is intended to accommodate, the interior of the bushing 84 may preferably be inwardly and forwardly beveled (Fig. I guiding the end of they pipe into the chuck when the pipe is pushed forward through the container, and as the bushing is frequently subjected tothe impact of the end of the pipe it is advantageous to make it removable as shown instead of integral with the container so' that if it becomes damaged it may be readily replaced. The jaws of the chuck are arranged to be moved in and out by rotation 4) so as to assist in of a grooved cam ring 85 provided with spanner holes for the introduction of a suitable tool to obtain the desired leverage for rotating it and cooperative with rollers 86 mounted on pins 87 secured to the jaws in such manner that when the ring is turned in one direction, the jaws will be forced inward to grip the work and when turned in the other direction will be withdrawn therefrom so as to free the work and permit its removal from the machine. Chucks of this general character are of well known construction and in common use.

For a purpose to be hereinafter described, a ring 88 is mounted around the annular chuck member 88 and held thereon by a collar 89 threaded onto the nose of the member, the ring being provided with spaced peripheral flanges forming a roove 90 between them. This ring is extende flange which forms the rear wall of the groove so as to abut against a flange 70 onthe end of the container in which position it is maintained by the collar 89 when the latter is screwed into position; thus ring 88 is constrained to move longitudinally as well as to rotate with the container. To facilitate adjustment 'of cam ring 85, the ring 88 is cut away segmently at difierent points above ring 85 so as to expose the latter and permit access to the spanner holes in it as clearly shownin Figs. 2 and 4:.

It will of course be understood that when positioning the pipe in the machine preparatory to its being threaded, the pipe is pushed forwardly through the container, bushing and chuck for a suitable distance to expose the end which is to be threaded and then clamped firmly by the chuck so as to turn therewith and in turn with the container, the

opposite end of the pipe being supported in any suitable manner. to permit the requisite rotation of the pipe. Preferably a limiting stop 91 is secured to the pedestal in position to engage the end of the pipe and arrest its movement through the container so that consecutive pieces of pipe will be projected the same distance beyond the container and thus occupy the same relative position with'respect to the cutters. I

Container driving mechanism Rotation of the container within its housing is effected through the medium of a worm gear 100 which is s lined to the container so as to turn therewitli while permitting longitudinal movement of the container with respect thereto; this worm gear is in constant meshing engagement with a worm 101 mounted on the container drive shaft 102 which is journaledfor rotation beneath the container and extends at right angles to its axis. This shaft, together with the master nut driving shaft and other parts to be presently described, may be mounted in a suitable "rearwardly beyond the frame 103 so formed and of such shape that after the shafts and other parts are assembled in it, the frame may be slid into the lower part of the housing through the opening in the front thereof which is thereafter closed by the covers 81, 81, levelling screws 10 1 be ing arranged to properly support and align the frame. This materially enhances convenience of manufacture as it enables the necessary machine work and assembly to be donemuch more readily than would be the case if the frame were not employed and the shafts were journaled directly in the housmg.

The worm 101 is keyed to shaft 102 so as to always turn therewith and is provided with an integral clutch-half 105 adapted for engagement by a double faced clutch 106 slidably mounted on a sleeve 107 rotatably disposed on the shaft; on this sleeve is rotatably mounted a gear 108 whose face adjacent the double faced clutch is provided with a clutchhalfrl09 adapted to cooperate therewith. Adjacent gear 108 a worm drive gear 110 is keyed on the sleeve, this gear being cooperative with a worm 111 disposed below shaft 102 upon a power shaft 112 which extends through the wall of the frame 103 and the housing and is connected through spiral gears 113, 113 housed in a casing 11 1 securedto the housing with a drive shaft 115 extending vertically to a point above the housing where it is connected through suitable gears housed in a casing 116 and a train of reduction gears housed in a casing 117 with a driving motor DR mounted on the housing cap. Thus when the motor DR is in operation and the double faced clutch engaged with clutch-half 105, worm 101, and in turn the container, will be driven from the motor through drive shaft 115, power shaft 112, worm 111, worm drive gear 110 and the double faced clutch which in the aforesaid position locks worm 101 to sleeve 107, while when the double faced clutch is disengaged from the clutch-half 105 as in Figs. 11 and 13, worm 101, worm gear 100 and the container with its attached parts will remain stationary even though sleeve 107 be rotating.

For manually effecting the engagement of the double faced clutch with the clutch-half 105 so as to start the rotation of the container, the double faced clutch is provided with a groove in which the arms of a fork 120 are seated; this fork is secured to a sliding shaft 121, mounted in lugs 122 carried by the frame 103 and which extends toward the front of the machine but'terminates short of the cover 81', secured to which is a hollow boss 123 in which is slidably mounted a spring pressed operating plunger 124 carrying an operating knob 125 and aligned with the shaft 121 in such pushed. inwardly it will move the operating manner that when shaft rearwardly so as to engage the double faced clutch with the clutch-half 105. Container translating means der to form a continuous thread to effect relative longitudinal movement between the work and the cutter vwhile the work and cutter are rotating relativelyto each other, each on its own axis, and to this end I therefore provide means for moving the container axially for the requisite distance with respect to the cutter, said means comprising a suitable master nut and screw, having, preferably, threads of a pitch greater than the pitch of the thread which is to be formed.-

Thus, for example, if the thread is to be formed with a pitch of ten to the inch, I prefer to utilize a master nut and screw having a pitch of one to the inch so that the neces-. sary longitudinal movement of the work with respect to the cutter may be obtained by effecting a relative rotation of the container and master screw (which operate as a unit) on one hand and the nut on the other through less than Under such conditions, when forming a ten-' pitch thread and utilizing a master screw with a pitch of one to the inch, relative revolution of the screw with respect to the nut, amounting to one-tenth of a complete revo-" lution is effective to move the screw and container longitudinally with respect to the nut for one-tenth of an 1nch which is the amount/ which the work must be moved longitudinal ly with respect to the cutter for each complete revolution made by the work in order to produce the desired helical thread. One of the advantages arising from the employment of a master screw and nut having threads of greater pitch than the pitch of the thread to be formed is that errors in the master threads instead of being directly produced in the thread in the work are only communicated thereto and reproduced therein in the ratio which the pitch of the latter bears to that of the former, resulting in a decided minimization of error in the finished thread; additionally, as a practical matter it is ordinarily easier to accurately machine a master screw and nut having threads whose eonvolutions are of relatively. great cross sectional area than when the convolutions are finer, as they must be when corresponding directly with those of the thread to be formed, while under operative conditions the large area of contact between the threads of the relatively moving master screw and nut minimizes the wear between the parts. Thus the accuracy of the master threads can ordinarily be made initially greater and canbe preserved for a much longer period of time with corresponding resulting accuracy in the threads produced in the work where the pitch acomplete revolution. 7

of the'master thread is made greater than that of the thread to be formed than is the case where the pitch of the master thread is similar to that of the latter.

I therefore provide the container with an annular master thread which is formed on the outer face of a ring 130 surrounding and keyed to the container so as to rotate therewith, the pitch of this thread for the reasons above stated being preferably greater than that of the thread which is to be formed. The master screw which may be either single or multiple and of any cross sectional form is cooperative with a correspondingly internally threaded annular nut 131 disposed within the'housing and prevented from 1on git-udinal movement by thrust bearings 132. Upon the ='outer periphery of the nut is formed a'worm gear which is at all times in meshing engagement with a worm 133 keyed on the master nut drive shaft 134 which extends-in the frame 103 parallel to the container drive shaft and is supported for revolution in suitable bearings mounted in that frame.

Since for the reasons already explained .it is necessary while the threading cutter is operating on the work to cause a predetermined longitudinal movement thereof relative to the cutter for each revolution of the work, means are provided by which the master nut will- ,be driven through the worm 133 in correspondence with the rotation of the container /but at a somewhat slower rate when a master screw of greater pitch than the thread to be formed is employed, so that the revolving container will be caused to progress gradually with respect to the nut in a longitudinal direction. Thus (Fig. 6) the means for driving the nut tvhile the thread is being formed may comprise a gear 135 keyed to shaft 102 and meshing with an idler gear 136 disposed at one end of a sleeve 137 rotatably mounted on a short shaft 138 located between shafts 102 and 134 and supportedin'suitable bearings, this idler gear in turn meshing with another gear 139 rotatably mounted on shaft 134. Splined to and capable of limited longitudinal movement on shaft 134 adjacent the rear end of gear 139 is an over-running clutch 140 having its face provided with clutch teeth cooperative with similar teeth on the face of the gear and so designed that when the gear is driven through gears 135 and 136 from the container drive shaft 102 the respective teeth willengage each other and lock the over-running clutch to continually -pressed toward the gear by a coil spring 141 surrounding the shaft, but when the clutch is itself driven through shaft 134 as hereinafter described, the teeth of the clutch will ride over the teeth of the gear. Hence rotation of shaft 102 is communicated to shaft 134 through gears 135, 136 and 139 and over-running clutch 140 in such mangear 139, the former being ner as to cause shaft 134 to rotate in the same direction as shaft 102 but the ratio of the gears in the train is so designed as to cause shaft 134 to turn at a slower rate than shaft 102; thus when the master screw is of ten times the pitch of the thread to be formed the ratio of the gears is such as to turn shaft 134 through nine-tenths of a revolution for each complete revolution of shaft 102 so that for each revolution of the container (which is driven from shaft 102), the master nut (which is driven from shaft 134) will make but ninetenths of a revolution, in consequence of which the container during each complete revolution will move longitudinally of the nut for a distance equal to one-tenth the pitch of the master screw,

It will be apparent that by changing the ratio of the train of gears between shafts 102 and 134 the amount of longitudinal progression of the container for each complete revolution thereof may be readily varied and thus that a thread of different pitch may be pro duced on the work without changing the master thread. Therefore to facilitate adjustment of the machine for the production of threads of two different pitches in this manner I dispose on shaft 102 a gear 135 and on shaft 134 a gear 139 corresponding respectively to gears 135 and 139 but having a different number of teeth from said gears and provide on the other end of sleeve 137 an idler gear 136 adapted to connect gears 135 and 139 when disposed between them. As the sleeve 137 is prevented in any suitable way from longitudinal movement on shaft 138 and the shaft, which is extended out of the housing and provided with a knob-137 for convenient manual operation, arranged to he slid endwise in its supporting bearings, it will be apparent that either of the idler gears 136, 136 may be thrown into mesh as desired thus giving a different speed ratio between shafts 102 and 134. A spring pressed stop pin 142 may be so arranged that its point will project into a slot 143 in shaft 138 provided with recesses at its ends adapted to receive the point of the pin so that when the latter is in either of the recesses, the shaft will be held in theproper position to align either the gear 136 or the gear 136' with the other gears of the train of which it is designed to form a part.

Container returning means A machine constructed in accordance with the preferred embodiment of my invention is so arranged that the work P will be moved to the left-when viewed as in Figs. 1 and 2 while aright hand thread is being cut and in the said figures the parts are shown in the position which they occupy after the work has been inserted in the machine but before the cutters are'moved to engagement therewith. Since the work and the container the container to rest.

move to the left during the cutting operation it is therefore necessary toprovide means for returning the container it initial or starting position from he position which it occupies when the thread. is finished and while such means may be of any convenient form, it is however extremely desirable that they be'of such character as to always return the container the same distance and then bring it to rest as by so doing the movement which the container undergoes while the thread is being cut will always be initiated from exactly the same point for each successive threading cycle with resulting accuracy and similarity in the threads produced on consecutive pieces of work.

The container returning means which I prefer to employ are so designed as to impart to the container the requisite return or forward movement by rotating the nut 131 while the container is positively prevented from rotation, this rotation of the nut being in the same direction as during the threading operation but preferably at a higher speed so as to provide a quick return. /Vith this end in view a small idler gear 146 is mounted on a'stub idler shaft 147 for constant meshing engagement with gear 108; this idler gear in turn meshes with a gear 148 keyed to and near the forward end of shaft 134, longitudinal movement of the gear on the shaft being prevented by spacer sleeves 149. Thus, when the double faced clutch 106 is moved forward so as to engage the clutchhalf on gear 108, the motion of sleeve 107 will be transmitted through gears 108, 146 and 148 to shaft 134 to cause the same to turn in the same direction in which it turned during the threading operation, but preferably, owing to the ratio of the gear train just referred to, at a somewhat higher speed, with consequent rotation of worm 133 and master nut 131. However, as the double faced clutch is now out of engagement with clutch-half 105 through which the drive of the container drive shaft 102 is normally effected, the latter is held stationary through the intermeshing engagement of worm 101 and worm gear 100 thus positively locking the container against rotation, with'the result that the rotation of the master nut which is itself prevented from longitudinal movement imparts a movement of longitudinal translation to the container so as to move it bodily forward to the position which it initially occupied at the commencement of the threading operation. Upon its arrival at such position, the double faced clutch is automatically disengaged from the clutch-half 109 by means presently to be described, thereby bringing During this return movement of the container and While the drive of shaft 134 is being effected through the gear train 108, 146 and 148 the teeth of the over-running clutch member 140 overrun the teeth on gear 139, which latter is ,held stationary with shaft 102, spring 141 yielding sufficiently to produce thisresult.

After the introduction and chucking of the work and at the commencement of the threading operation proper, the double faced clutch, as hitherto stated, is manually moved from neutral position (Fig. 13) into engagement with clutch-half 105 (Fig. the operating knob 125 and remains in such engagement until the thread is completed, but immediately thereafter the double faced clutch is automatically disengaged from clutch-half 105 and moved into engagement with clutch-half 109 (Fig. 15) so as to effect the return of the container to initial or start-, ing position after which the double faced clutch is automatically moved-out of'engagement with clutch-half 109 to neutral position so as to stop the motion of both shafts 102and 134 at the completion of the thread- I ing cycle; the means which I prefer to employ for automatically efiecting these movements of the double faced clutch will now be described:

Pivoted to a boss 150 on frame 103 is a generally L-shaped latch lever 151 havingat'one end a hooked toe 151 adapted to engage over the lower corner of a lug 152 pinned to the sliding shaft 121. ;At its other end, the latch lever is connected to a spring 153 in turn connected to a pin 154 disposed on shaft 121 in such manner that when the shaft is pushed inwardly the spring will tend to raise the lever so as to engage its hooked toe over lug 152 and thus hold the shaft in inward position to maintain the double faced clutch in engagement with clutch-half 105 (Fig. 14). Surrounding shaft 121 and disposed between one of the lugs 122 in which it is mounted and a collar 155secured to the shaft is a compression coil spring 156 which operates to move the shaft outwardly when the latch lever is disengaged from lug 152 so as to bring the double faced clutch into engagement with the other clutch-half 109 as in Fig. 15. That arm of the-latch lever to which spring 153 is connected carries a transversely extending pin 157 which extends between two limit stops 158 and 158 disposed on the shaft and which, when the latter is reciprocated, operate to positively move the lever intoand out of lug-engaging position. The extent of longitudinal movement permitted to shaft 121 is regulated by a stop pin 159 carried by one of the shaft supporting lugs and working in a slot 159 formed in the shaft. It will thus be apparent that when the shaft is pushed manually inward through the medium of knob 125 to engage the double faced clutch with clutch-half 105, latch lever 151 thereafter operates to maintain such engagement until it is positively forced away from lug 14) by means of' 152 by means new to be described, thereby permitting spring 156 to move the shaft in the opposite direction that is, outwardly, to

engage the double faced clutch with the clutch-half 109.

Positioned between shafts 102 and 134 and in a plane considerably thereabove is a bracket 160-horizontally bored for the passage of a shaft 161 surrounded by a bushing 162 nonrotatable with respect to the bracket, which latter is provided with a supporting base 160: secured to a horizontal web integral with the cover 81. Shaft 161 projects over shaft 121 and carries aligned therewith a depending forked finger 163 whose free end depends over shaft 121 and thus lies in the path of lug 152.

The container drive shaft 102 is extended to a point adjacent the forward extremity of frame 103 to there support a worm 165 which meshes with a gear 166 disposed above the worm and journaled for rotation on the adjacent end of bushing 162 which projects beyond the end of bracket 160. In like manner shaft 134 is continued forwardly to support a worm 167 meshing with a worm gear 168 disposed thereabove and journaled for which is desirably provided with a pocket for the reception of gear 170. Shaft 171 extends horizontally in the general direction of the pedestal and is connected through a telescopic shaft 172 and universal joints 173 with a shaft 174 journaled in the base of the pedestal and carrying a gear 175 meshing with another gear 176 keyed to the hub of the timing disc 17 7 which is rotatably mounted on'a stud shaft 17 8 carried by the base of the pedestal, the arrangement being such that the timing disc lies in a vertical plane and adjacent the rear face of the former. Thus the timing gear, through the medium of the mechanlsm just described, isrotated whenever gear 168 revolves and as this gear is always in motion whenever shaft 134 is revolving it will be apparent that the timing disc may be employed, as hereinafter more fully described, to cause the various elements of the machine to perform their respective functions in properly timed relation with each other, the ratio of the gearing through which the timing disc is loosely mounted on the hub'of gear 166 and the face of the gear provided with two pins 

